Dysregulation of Glutamine Synthetase in Human Temporal Lobe Epilepsy: The main objective of this K08 proposal is to facilitate the applicant's development towards independence as a physician-scientist investigator in basic science/translational research. This will be achieved through a series of complementary educational and mentored research training experiences in which the applicant will learn state-of-the-art methodologies in molecular biology, proteomics, cell culture and flow cytometry. The scientific question addressed by these methodologies is: what is the mechanism underlying the down-regulation of glutamine synthetase in the hippocampus of patients with mesial temporal lobe epilepsy? This question is important because experimental inhibition of glutamine synthetase in the hippocampus of animals causes epileptic seizures followed by cessation of the seizures once the enzyme has been restored. The specific aims of this proposal are: 1) Analysis of transcriptional regulation of glutamine synthetase using laser capture microdissection, quantitative real time PCR, and in situ hybridization on surgically resected human epilepsy hippocampi. 2) Analysis of posttranslational modification of glutamine synthetase by 2D gel electrophoresis, immunological techniques, and mass spectrometry. 3) Establish an in vitro system for experimental studies of glutamine synthetase regulation, using acute and chronic cultures of astrocytes from human epileptogenic hippocampi combined with flow cytometric analysis of the cultured cells. Layman's Abstract: People with temporal lobe epilepsy have low levels of brain glutamine synthetase, an enzyme that transforms glutamate to the non toxic chemical glutamine. The goal is to understand why the enzyme is down-regulated, so that new antiepileptic treatments targeting glutamine synthetase can be developed.